Multiwavelength Raman fiber laser based on polarization maintaining fiber loop mirror and random distributed feedback

We experimentally demonstrate a configuration to realize multiwavelength generation in a Raman fiber laser structure. The system includes a fiber loop mirror (FLM) containing a piece of polarization maintaining (PM) single mode fiber, and a 1 km-long passive fiber which is core pumped by a 1120 nm pump laser providing Raman amplification and random distributed feedback via Rayleigh scattering. Up to 1 W multiwavelength laser output is realized due to interference between modes supported by the FLM. As a consequence, a 35 nm bandwidth multiwavelength spectrum from 1155 to 1190 nm with similar to 0.75 nm spacing (OSNR similar to 10 dB) is obtained.